Comparison of Posttreatment Stability Between Mandibular Setback Surgery-Early and Conventional Surgery in Class III Patients: A 4.6-Year Follow-Up.

OBJECTIVES: This retrospective study aims to compare long-term stability between the mandibular setback surgery-early (MSE) approach, involving minimal orthodontics, and the mandibular setback conventional surgery (MCS) approach, involving sufficient orthodontics, in Class III patients with mandibular prognathism. METHODS: Among 210 patients who underwent orthognathic surgery, a total of 40 subjects were enrolled based on standardized inclusion criteria: only mandibular surgery, <5 mm setback difference between right and left of the mandible, orthodontics with fixed appliances, and more than 2 years of follow-up after treatment. These patients were allocated to the MSE (n = 20) and MCS groups (n = 20) according to the duration of presurgical orthodontics. Changes in cephalometric measurements were compared between the MSE and MCS groups before surgery (T0), 1 month after surgery (T1), at the end of treatment (T2), and posttreatment retention (T3). RESULTS: The MSE and MCS groups had a mean presurgical orthodontic duration of 2 and 9.5 months, respectively. From T1 to T2, the MSE group showed a significantly larger forward movement of the mandible than the MCS group (2.1 versus 0.7 mm; P < 0.001). In addition, from T2 to T3 (average 4.6 years), the MSE group presented anterior relapse of 0.6 mm in the mandible, but there were no statistically significant intergroup differences. CONCLUSION: Although the MSE group showed greater postsurgical forward mandibular relapse than the MCS group, the two groups exhibited similar skeletal and dental stability during the posttreatment retention.

Accuracy of intraoral scan images in full arch with orthodontic brackets: a retrospective in vivo study.

OBJECTIVES: The purpose of this retrospective study was to evaluate the accuracy of intraoral scan (IOS) images in the maxillary and mandibular arches with orthodontic brackets. MATERIAL AND METHODS: From digital impressions of 140 patients who underwent orthodontic treatment, consecutive IOS images were selected based on standardized inclusion criteria: Two pre-orthodontic IOS images (IOS1 and IOS2) of permanent dentition with fully erupted second molars and IOS images obtained immediately after orthodontic bracket bonding (IOSb). Superimpositions were performed to evaluate the reproducibility of repeated IOS images. Accuracy of IOSb images was analyzed by comparing the average surface errors between IOS1c and IOS2c images, which were IOS images cut based on the same region of the interest as between IOS1 and IOSb images. RESULTS: A total of 84 IOS images was analyzed. The average surface errors between IOS1 and IOS2 images were 57 ± 8 µm and 59 ± 14 µm in the maxillary and mandibular arch, respectively, and their reliability was almost perfect. The average errors between IOSb and IOS1c images exhibited an increase, which measured 97 ± 28 µm in the maxillary arch and 95 ± 29 µm in the mandibular arch. These surface deviations between IOSb and IOS1c images were significantly larger in each region as well as entire dentition (P < 0.001) compared to those between IOS1c and IOS2c images. CONCLUSIONS: The average surface errors of the scans with brackets showed increased values compared with those without brackets. This suggests that orthodontic brackets could affect the trueness of intraoral scan images. CLINICAL RELEVANCE: It is necessary for clinicians to consider the effect of brackets on digital impression when using IOS images in orthodontic patients.

Soft Tissue Changes After Clockwise Rotation of Maxillo-Mandibular Complex in Class III Patients: Three-Dimensional Stereophotogrammetric Evaluation.

OBJECTIVES: To evaluate the linear, angular, and volumetric changes of soft tissue after clockwise repositioning of the maxillo-mandibular complex in skeletal class III patients using three-dimensional (3D) stereophotogrammetry and to determine the correlation between changes in the skeletal and soft tissue variables. METHODS: This study included 18 skeletal class III patients who underwent two-jaw surgery; superior impaction and clockwise rotational movement of the maxilla with the rotation center at upper incisors, and setback of the mandible. Lateral cephalograms and 3D photographs taken before and 6 months after surgery were compared. RESULTS: After maxillary impaction of anteriorly 1.7 mm and posteriorly 3.1 mm, and mandibular setback of 8.7 mm, the volume of lower lip and chin region decreased significantly by 33.6 cm3 (13% net change, P < 0.001), while paranasal and upper lip region volume increased by 3.2 cm3 (2%) and 7.2 cm3 (4%), respectively. CONCLUSION: The clockwise rotation of maxillo-mandibular complex in class III patients significantly reduced lower lip and chin volume with minimal increase in paranasal and upper lip volumes. 3D stereophotogrammetry can provide quantitative evaluation of facial soft tissue volumetric changes.

Factors Related to Relapse After Mandibular Setback Surgery With Minimal Presurgical Orthodontics.

PURPOSE: The aims of this study were to compare the presurgical conditions, surgical changes, and postsurgical changes in patients with skeletal Class III malocclusion with different degrees of horizontal relapse after mandibular setback surgery (MS) with minimal presurgical orthodontics (MPO) and to identify the factors contributing to this relapse. MATERIALS AND METHODS: For this retrospective study, 33 consecutive patients who underwent MS-MPO were selected. Lateral cephalograms were taken preoperatively (T0), 1 month after surgery (T1), and at orthodontic debonding (T2). Patients were divided into low relapse (LR; n = 18; relapse, <1 mm) and high relapse (HR; n = 15; relapse, >2 mm) groups based on the cephalometric distance of mandibular horizontal relapse. Paired t test, independent t test, and Pearson correlation analysis were used to evaluate surgical (T0 to T1) and postsurgical (T1 to T2) changes in the skeletodental variables and to explore the relation between surgical changes and horizontal relapse. RESULTS: Compared with the LR group, the HR group exhibited more upward movement with counterclockwise rotation of the mandible from T1 to T2. The HR group presented at T0 with a more prognathic mandible, greater vertical facial height, and a positive overbite. In addition, the HR group presented more posterior movement with clockwise rotation of the mandible, increased overjet, and decreased overbite from T0 to T1. Horizontal relapse of the mandible was positively correlated with the amount of setback and clockwise rotation of the mandible and the change in overjet and was negatively correlated with the change in overbite. CONCLUSIONS: Mandibular instability was related to the extent of setback and clockwise rotation of the mandible, decreased overbite, and increased overjet during MS-MPO.

Biocompatibility and Efficiency of Biodegradable Magnesium-Based Plates and Screws in the Facial Fracture Model of Beagles.

PURPOSE: A biodegradable magnesium alloy system has been developed as a substitute for conventional plates and screws made of titanium or absorbable polymer. However, previous studies were limited to small animal experiments using screws or wires. In the present study, we preliminarily evaluated the biocompatibility and effectiveness of human standard-size biodegradable magnesium-based plates and screws in facial fractures of beagles. MATERIALS AND METHODS: Fracture lines were created bilaterally in the zygomatic arches of 6 beagles. They were fixed in situ with plates and screws made of magnesium alloy mixed with calcium and zinc (experimental group) or absorbable polymer (control group). Laboratory testing, radiologic imaging, histologic analysis, and mechanical testing were performed 4 weeks postoperatively. RESULTS: Inflammatory reactions were not significantly increased in any animal. Mechanical testing showed greater ultimate load and structural stiffness in the experimental group. In the histologic analysis, the void area and bone regeneration area were increased in the experimental, and the implant area and soft tissue area were increased in the control group. Radiologically, 3-dimensional micro-computed tomography showed no differences in the bone gap area between the 2 groups. A temporary increase in hydrogen gas around the magnesium implants regressed spontaneously and did not affect bone healing significantly. CONCLUSIONS: Magnesium-based biodegradable plates and screws showed good biocompatibility and offered considerable stability for fixating facial bone fractures in the early bone-healing process. These results show the possibilities for the future development of magnesium alloy plates and screws for craniomaxillofacial fixation in humans.

Prospective Study on the Intraoperative Blood Loss in Patients with Cleft Palate Undergoing Furlow's Double Opposing Z-Palatoplasty.

BACKGROUND: Blood loss during cleft palate surgery has been investigated in previous research, but there is no report regarding blood loss when performing Furlow's double opposing Z-plasty (DOZ). In the present study, we evaluated intraoperative blood loss in patients with cleft palate who underwent the DOZ procedure. MATERIALS AND METHODS: Intraoperative blood loss was prospectively investigated in 59 patients undergoing palatoplasty with DOZ by a single surgeon between August 2012 and July 2013. Demographic factors and clinical status, including cleft type and palatal gap, were recorded. Blood loss was evaluated by measuring the change in weight of a suction bottle, suction line, and gauze balls. RESULTS: Mean blood loss was 16.61 ± 10.33 mL, which accounted for 5% of total blood volume. Male sex, older age, severe cleft type, larger palatal gap, relaxed incision, and increased operative time contributed to greater blood loss. The amount of intraoperative bleeding could be predicted by the following equation: Blood loss = -5.64 + 6.18 (male patients) + 7.58 (severe type cleft) + 0.88 X age (months) + 0.84 X palatal gap (mm). CONCLUSIONS: We found that the DOZ technique causes mild blood loss, but bleeding amount tended to increase in older male patients with a severe cleft and a larger palatal gap. The use of relaxed incisions during palatoplasty and prolonged operation times also contributed to greater blood loss.

Roles of Polycaprolactone Membrane on Guided Bone Formation in High-Speed Distraction of Experimental Design Cranium.

BACKGROUND: The aim of this research was to investigate whether covering of the distracted cranial bone segment with a polycaprolactone (PCL) membrane (guided bone formation) would accelerate the process of osteogenesis in high-speed distraction of adult rabbit. METHODS: Eighteen 24-weeks old, 3.0 to 3.5  kg, male New Zealand rabbits underwent routine gradual cranium distraction (group 1), distraction at high speed without the membrane (group 2), and distraction at high speed with a PCL membrane covering the cranium at the distraction gap (group 3). Five days after the cranial osteotomy, the distraction process was initiated at 3  mm per day (1.5  mm twice a day) in group 2 and group 3, and 1  mm per day (0.5  mm twice a day) in group 1 until 10  mm of length gain was achieved. At the consolidation 4 and 6 weeks, the bone mineral density was analyzed by a computerized tomography imaging protocol. The bone formation ratio of each group was compared with Hematoxylin and Eosin stain. The collagen formation of each group was analyzed by Massons' trichrome staining. RESULTS: Radiographic imaging and quantitative data indicated a significant increase in bone mineral density in group 1 and group 3 compared with group 2. Bone formation ratio in histologic analysis showed an increase in group 1 and group 3. Collagen synthesis in group 2 was significantly increased in distraction gap. In group 3, collagen fibers were significantly decreased underneath the PCL membrane. CONCLUSIONS: Polycaprolactone membrane covering the bone distraction gap provides an environment for faster bone formation in high-speed distraction.

Curvilinear transformation of z-shaped upper lip scar by diamond-shaped excision in secondary cleft lip deformities: a photogrammetric evaluation.

Purpose : The visible Z-shaped upper lip scar that occurs after the Tennison and Randall triangular flap technique remains a cleft stigma. Herein, we present our curvilinear transformation technique for the Z-shaped upper lip scar by diamond-shaped excision and evaluate the results using photogrammetric analyses. Patients and Methods : From 1997 to 2006, 23 patients with secondary cleft lip deformity with the visible Z-shaped upper lip scar underwent correction with the technique. The scar was excised in the diamond shape above the muscle. After curvilinear closure, the elongated length of the upper lip was excised just below the nostril sill, as the measured Cupid's bow height discrepancy. The result was assessed by the authors' standardized photogrammetry technique. Results : There was a statistically significant decrease between the preoperative central limb of the Z-shaped scar and the width of the postoperative curvilinear upper lip scar. The pre- and postoperative Cupid's bow height differences were not statistically significant. Conclusions : The curvilinear transformation of the Z-shaped scar is an efficient procedure that provides (1) a significant decrease in the width of an upper lip scar to make it less conspicuous, (2) incorporation of the scar into the philtral column, (3) a biconcave natural philtral column shape in frontal view, and (4) formation of the natural concave philtral contour in profile view.

Restoration of a vertical alveolar bone defect by orthodontic relocation of a mesially impacted mandibular first molar.

An impacted mandibular first molar tends to cause serious bone defects of the adjacent teeth. When choosing between the 2 typical treatment options-extraction or orthodontic relocation of the impacted tooth-the decision should be based on assessment of the prognosis. A 22-year-old man with severe mesioangulation and impaction of the mandibular first molar and a related vertical bone defect on the distal side of the second premolar was treated with extraction of the second molar and orthodontic relocation of the first molar with a retromolar miniscrew. Comprehensive orthodontic treatment involving premolar extraction was conducted. Strategic extraction of the molar and adequate orthodontic movement helped to restore the bone structure on the affected side. This case report suggests the effectiveness of restoration of bone defects by using viable periodontal tissues around the impacted tooth for the longevity of the periodontium.

Influence of modified Furlow double opposing Z-plasty on mandibular growth in Oriental patients with cleft palate and/or lip.

The purpose of this study was to statistically analyze mandibular growth disturbance in the Oriental cleft population and compare this with that of non-cleft children through cephalometric analysis. Thirty-six children with cleft palates, repaired using a modification of Furlow double opposing Z-plasty, were chosen. Comparative analyses among 3 types of cleft were performed. Statistical analyses of 8 linear and angular measurements were performed in cleft patients and the non-cleft population using Fisher Z-transformation. Comparative analysis showed no significant difference among the 3 types of cleft. In the Oriental cleft group treated with modified double opposing Z-plasty, the spatial position of the mandible showed significant differences compared with the non-cleft group. A backward inclination of the anterior surface of the mandible and downward rotation of the mandibular body were identified. Some of our results regarding gonial angle and length of the mandibular body conflicted with previous Western studies.

Statistical analysis using the OMENS classification in Oriental patients with hemifacial microsomia: a comparative analysis with Western centers.

The purpose of this study was to analyze the statistical association between variable clinical phenotypes of the orbit, mandible, ear, nerve, soft tissue (OMENS) classification system in Oriental patients with hemifacial microsomia (HFM) and compare the data of Oriental children with data from other Western centers. One hundred consecutive patients with HFM referred to the Seoul National University Children Hospital were chosen between March 2009 and April 2010. They were classified according to the OMENS classification system, and statistical analyses were performed. The total OMENS scores were correlated significantly with all 5 component scores. In comparison with the previous data of Western centers, the orbit and ear components had statistically higher severity. Our retrospective study in Oriental children demonstrated that the pathophysiology of HFM is a complex process and that the components of HFM have a close relationship. For the ethnic difference, further etiologic studies on the molecular basis are required.

Timely relocation of subapically impacted maxillary canines and replacement of an ankylosed mandibular molar are the keys to eruption disturbances in a prepubertal patient.

Eruption disturbances such as impaction and ankylosis complicate orthodontic treatment because soft-tissue and hard-tissue considerations must be taken into account. Treatment is further complicated when such eruption disturbances occur in a growing patient. Extraction of impacted or ankylosed teeth can be an option that carries the weight of additional prostheses and bony defects, whereas exposure or luxation followed by orthodontic traction can preserve the patient's teeth and bony structure with improved esthetics. Therefore, an accurate diagnosis is needed in establishing an efficient and effective force system to achieve the desired tooth movements with few unwanted sequelae. This case report describes the process of differential diagnosis with the aid of 3-dimensional imaging in constructing a force-driven system, using the centers of resistance as reference points, to successfully bring a pair of impacted maxillary canines into alignment and protract a mandibular molar to achieve an acceptable occlusion in an adolescent girl.

Mandibular posterior anatomic limit for molar distalization.

INTRODUCTION: The purpose of this study was to investigate the mandibular posterior anatomic limit for molar distalization. METHODS: Three-dimensional computed tomography scans were obtained on 34 adults with a skeletal Class I normodivergent facial profile and a normal occlusion. Posterior available space was measured at the crown and root levels along the posterior occlusal line connecting the buccal cusps of the first and second molars on the axial slices. It was also measured at the occlusal level on the lateral cephalograms derived from the computed tomography scans. The measurements on the cephalograms were used to predict the actual posterior available space determined by computed tomography and to determine the presence of root contact with the inner lingual cortex by linear regression and discriminant analyses, respectively. RESULTS: The posterior available space was significantly smaller at the root level than at the crown level. Root contact was observed in 35.3% of the 68 roots. The posterior available space measured on the lateral cephalograms resulted in a regression equation with a coefficient of determination of 0.261 to predict actual available space and correctly identified root contact in 66.2% of cases with a threshold value of 3.9 mm. CONCLUSIONS: The posterior anatomic limit appeared to be the lingual cortex of the mandibular body. Computed tomography scans are recommended for patients who require significant mandibular molar distalization.

Reliability of Artificial Intelligence-based Cone Beam Computed Tomography Integration with Digital Dental Images.

This study aimed to introduce cone-beam computed tomography (CBCT) digitization and integration of digital dental images (DDI) based on artificial intelligence (AI)-based registration (ABR) and to evaluate the reliability and reproducibility using this method compared with those of surface-based registration (SBR). This retrospective study consisted of CBCT images and DDI of 17 patients who had undergone computer-aided bimaxillary orthognathic surgery. The digitization of CBCT images and their integration with DDI were repeated using an AI-based program. CBCT images and DDI were integrated using a point-to-point registration. In contrast, with the SBR method, the three landmarks were identified manually on the CBCT and DDI, which were integrated with the iterative closest points method. After two repeated integrations of each method, the three-dimensional coordinate values of the first maxillary molars and central incisors and their differences were obtained. Intraclass coefficient (ICC) testing was performed to evaluate intra-observer reliability with each method's coordinates and compare their reliability between the ABR and SBR. The intra-observer reliability showed significant and almost perfect ICC in each method. There was no significance in the mean difference between the first and second registrations in each ABR and SBR and between both methods; however, their ranges were narrower with ABR than with the SBR method. This study shows that AI-based digitization and integration are reliable and reproducible.

Comparison of posttreatment stability after total mandibular arch distalization with mini-implants and mandibular setback surgery.

OBJECTIVES: To compare posttreatment stability in skeletal Class III patients between those treated by total mandibular arch distalization (TMAD) with buccal mini-implants and those by mandibular setback surgery (MSS). MATERIALS AND METHODS: The samples included 40 Class III adults, 20 treated by TMAD using buccal interradicular mini-implants and 20 treated with MSS. Lateral cephalograms were taken at pretreatment, posttreatment, and at least 1-year follow-up, and 24 variables were compared using statistical analysis. RESULTS: Mandibular first molars moved distally 1.9 mm with intrusion of 1.1 mm after treatment in the TMAD group. The mandibular incisors moved distally by 2.3 mm. The MSS group exhibited a significant skeletal change of the mandible, whereas the TMAD group did not. During retention, there were no skeletal or dental changes other than 0.6 mm labial movement of the mandibular incisors (P < .05) in the MSS group. There was 1.4° of mesial tipping (P < .01) and 0.4 mm of mesial movement of the mandibular molars and 1.9° of labial tipping (P < .001) and 0.8 mm of mesial movement of the mandibular incisors in the TMAD group. These dental changes were not significantly different between the two groups. CONCLUSIONS: The TMAD group showed a slightly decreased overjet with labial tipping of the mandibular incisors and mesial tipping of the first molars during retention. Posttreatment stability of the mandibular dentition was not significantly different between the groups. It can be useful to plan camouflage treatment by TMAD with mini-implants in mild-to-moderate Class III patients.

Comparison of treatment effects between two types of facemasks in early Class III patients.

OBJECTIVE: To compare the short-term treatment effects between two types of facemasks in skeletal Class III patients. MATERIALS AND METHODS: This retrospective study included 40 skeletal Class III subjects (mean age: 7.7 years) who had been treated with protraction facemasks with forehead straps (PFFS) or Petit type facemasks (PTF). Lateral cephalograms were analyzed at pretreatment (T1) and posttreatment (T2) with an average interval of 9 months. RESULTS: At T1, PFFS and PTF groups showed similar sagittal, vertical dentoskeletal patterns. From T1 to T2, both groups presented significant forward movement of the maxilla, posterior movement and clockwise rotation of the mandible (all p < .001), labioversion of the maxillary incisors, and linguoversion of the mandibular incisors. They showed increased overjet (p < .001). Although there were no significant differences in the number of changes in most dentoskeletal variables between the two groups, the PFFS group showed more anterior rotation of the palatal plane and backward rotation of the mandible compared to the PTF group, resulting in a significant decrease (-0.42 mm) in overbite (p < .05). CONCLUSIONS: Both PFFS and PTF showed no significant differences in most skeletal and dental changes, except for overbite. These findings might be helpful for clinicians in selecting the types of facemasks for growing Class III malocclusion patients.

Rehabilitation of severe dentofacial deformity after early radiotherapy of retinoblastoma: a case report.

BACKGROUND: Retinoblastoma is an intraocular cancer of infancy and childhood, which has been treated with radiation therapy and chemotherapy. Radiation on growing patients can cause deterioration in maxillofacial growth and development that leads to severe skeletal discrepancies between the maxilla and mandible, and dental problems such as crossbite, openbite, and hypodontia. CASE PRESENTATION: We present the case of a 19-year-old Korean man with chewing disability and dentofacial deformities. He had undergone enucleation of the right eye and radiation therapy of the left eye due to retinoblastoma 100 days after birth. Subsequently, he received cancer therapy for the secondary nasopharyngeal cancer at the age of 11 years. He was diagnosed with severe skeletal deformity including sagittal, transverse, and vertical growth deficiency of the maxilla and midface, and with class III malocclusion, severe anterior and posterior crossbite, posterior openbite, multiple missing upper incisors, right premolars, and second molars, and impaction of the lower right second molars. To restore impaired functions and esthetics of the jaw and dentition, the orthodontic treatment combined with two jaw surgery was performed. At the end of surgical orthodontics, dental implants were placed for prosthetic treatment of missing teeth. Additional plastic surgery for zygoma elevation was done with calvarial bone graft followed by fat graft. Facial esthetics and occlusal functions of patient were favorably enhanced with the improvement of skeletal discrepancy and the rehabilitation of maxillary dentition by prosthetic work. At the 2-year follow-up, the skeletal and dental relationships and implant prosthetics were well maintained. CONCLUSION: In an adult patient with dentofacial deformities caused by early cancer therapy in the head and neck area, interdisciplinary interventions including additional plastic surgery of zygoma depression and prosthetic work of missing teeth as well as surgical-orthodontic treatment could establish favorable facial esthetics and oral rehabilitation.

New approach for the surgico-orthodontic treatment of hemifacial microsomia.

One of the important clinical findings in hemifacial microsomia (HFM) is facial asymmetry (FA) with unilateral underdevelopment and malformation of the mandible and/or maxilla. Unilateral distraction osteogenesis (UDOG) of the mandible has been used for correction of FA in HFM patients. However, return to the original FA status often occurs because of contraction of the distracted bony segment of the mandible and insufficient compensatory downward growth and skeletal midline correction of the maxilla on the affected side. Although bimaxillary UDOG procedure in the maxilla with Le Fort I osteotomy and the mandible with ramus osteotomy was suggested as an alternative treatment modality, it has some disadvantages including elongation of the face, inaccuracy of vector control, and less predictable results. Occlusal plane canting, skeletal midline deviation of the maxilla, and unilateral mandibular hypoplasia might be simultaneously corrected by fixation of the maxilla into a proper position after Le Fort I osteotomy and UDOG of the mandible. Three-dimensional virtual simulation using three-dimensional computed tomography data could help to accurately predict surgical outcomes. In addition, transarch elastic traction from the orthodontic mini-implants on the unaffected side of the mandible to the maxillary posterior teeth on the affected side can produce a plastic molding of the regenerated bone in the distraction area of the mandible and induce compensatory dentoalveolar downward development of the maxillary posterior teeth. Therefore, the purpose of this article was to introduce a new approach for the surgico-orthodontic treatment consisting of simultaneous maxillary fixation and unilateral mandibular distraction with transarch elastic traction in HFM patients.

Accuracy of a surface-based fusion method when integrating digital models and the cone beam computed tomography scans with metal artifacts.

The aim of this study was to evaluate the intra- and inter-observer reliability of maxillary digital dental model integration into cone-beam computed tomography (CBCT) scans to reconstruct three-dimensional (3D) skeletodental models for orthognathic patients. This retrospective study consisted of CBCT and digital maxillary dentition images of 20 Class III orthognathic patients. After two repeated fusions of digital cast images with reconstructed CBCT images by a digital engineer and an orthodontist respectively, the 3D coordinate values of the canines, first molars, and central incisors were evaluated. The intra- and inter-observer reliability of 3D positions of maxillary teeth were compared using intraclass correlation coefficients (ICCs). Intra-observer reliability of x-, y-, and z-coordinate values of maxillary teeth showed significant and excellent agreement in an engineer (0.946 ≤ ICC ≤ 1.000) and an orthodontist (0.876 ≤ ICC ≤ 1.000). The inter-observer reliability of the y- and z-coordinates of each tooth was significantly excellent or good, but that of the x-coordinates showed insignificantly poor to moderate agreement. This study showed that the integration of maxillary digital models into CBCT scans was clinically reliable. However, considering the low inter-observer reliability on the x-coordinates of dentition, clinical experience and repeated learning are needed for accurate application of digital skeletodental model in orthognathic patients.

Displacement pattern of the maxillary arch depending on miniscrew position in sliding mechanics.

INTRODUCTION: This clinical study was performed to evaluate the anteroposterior and vertical displacement patterns of the maxillary teeth in sliding mechanics depending on the position of interradicular miniscrews after the extraction of premolars. METHODS: Thirty-six women requiring maximum incisor retraction because of bialveolar protrusion were divided into 2 groups: group A (n = 18), miniscrew between the premolar and the molar, and group B (n = 18), miniscrew between the premolars. Cephalometric measurements for skeletal and dental changes were made before and after space closure. RESULTS: In both groups, significant incisor retraction with intrusion of the root apex was noted, with no significant change in the first molar position. Group B displayed significantly greater intrusion at both the incisal tip (1.59 ± 1.53 mm) and the root apex (2.89 ± 1.59 mm) than did group A. In spite of the mean reduction of the vertical skeletal measurements, we failed to find significant skeletal changes. CONCLUSIONS: Miniscrews provided firm anchorage for anterior retraction. Selection of the placement site appeared to be an important determinant for the resultant displacement pattern of the incisor segment. Discriminative intrusion or retraction might be obtained via strategic miniscrew positioning.